The present invention relates to air diffusers and deflector structures therefor.
A known form of air diffuser comprises a series of blades that are each generally inclined laterally at an angle to an axis of the diffuser. Such air diffusers are commonly found in a ceiling where air is to be introduced in a one, two, three or four way air stream along the ceiling. The air stream velocity is gradually reduced as it moves along the ceiling and is entrained or mixed with the room air. Sometimes, insert devices are used in such air diffusers to spread the air stream and reduce its throw. ASHRAE defines "throw" as the horizontal or vertical axial distance an air stream travels after leaving an outlet before maximum stream velocity is reduced to a specified terminal velocity (e.g. 50, 100, 150 or 200 feet per minute). The nature or shape of the air distribution pattern can often usefully be judged by considering an isovel pattern. An isovel pattern links points in the air flow having equal velocity e.g. 50 fpm.
With the use of such insert devices, a four way essentially cruciform isovel pattern tends, for example, somewhat toward a radial or circular pattern, while a three way pattern approaches somewhat a semi-circular isovel pattern. As a result, more air can be introduced into the room with less drafts, since throw (and thus air velocity near the diffuser) is reduced. Shorter throws indicate more entrainment and better mixing with room air near the diffuser.
Known insert devices of which applicant is aware are not as efficient as may be considered desirable in reducing throw and promoting a more nearly uniform radial isovel pattern.